Police in Arizona have arrested a 20-year-old man over allegations that he raped a woman live on the internet.

According to media reports, the man - who comes from Surprise, a suburb of Phoenix - was taken into custody on charges of sexual assault, kidnapping and taking a surreptitious photograph, after a police investigation uncovered footage of the incident.

Court documents allege that the event took place in February, following a night when the man and a female friend got drunk. According to the affidavit, the man waited until the woman had fallen asleep and then set up a webcam before streaming the assault on the internet - apparently making a series of comments and jokes throughout the 30 minute broadcast.

"She said while he was doing this he was laughing and making comments," the affidavit states. "She said [he] made comments about how the victim would never know what was happening to her because she was 'passed out.'"

The woman was apparently unaware of what happened until friends alerted her, having found pictures of the incident online after it occurred. A witness who saw the stream live online reported it to police at the time, but it has taken investigators more than three months to locate any evidence of the recording.

While sex crimes have surfaced online before - often becoming part of police investigations into organised sexual abuse or paedophile rings in the process - the prevalence of video streaming services has made it easier for bragging criminals to broadcast their activities... and to get caught as a result.

Last year police in Florida launched an investigation after a 19-year-old man appeared to kill himself live online - with some viewers allegedly goading him to complete the act. While several of the 185 viewers contacted police to warn them what was happening, others encouraged him to "do the world a favour".

In California, meanwhile, a 49-year-old woman was convicted last year of a number of charges relating to the suicide of a 13-year-old neighbour. Megan Meier, from St Louis, Missouri, killed herself in 2006 after being bullied on MySpace. Lori Drew, who lived next door to Meier, was accused of coordinating the attacks and found guilty of using a computer without authorisation for her role in the death of the teenager. She has yet to be sentenced, but could face up to three years in prison.